Cyclic Imide Coating for Heat Sealable Substrates
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Solution Overview
Problem
Current heat sealable packaging materials, such as those using laminated thermoplastic layers like LDPE on paper or cardboard, are difficult to recycle and result in waste that can only be incinerated for energy recovery, and require minimum thickness to maintain barrier properties, making them heavy and inefficient.
Innovation Solution
A heat sealable substrate with a cyclic imide coating layer that provides both heat sealability and water barrier properties, using a copolymer of cyclic imides and vinylic co-monomers dispersed in a waterborne formulation, allowing for thinner, lighter, and more recyclable packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laminated thermoplastic layers like LDPE are used on paper or cardboard to provide heat sealability and water barrier properties, then good sealing performance and barrier properties are achieved, but the packaging material becomes difficult to recycle and heavier
Solution Approach 1:
The invention extracts the heat sealable and water barrier functionality from thick laminated thermoplastic layers and concentrates it into a thin coating layer containing cyclic imide copolymer particles. This extraction allows the bulk paper or cardboard to remain recyclable while the thin coating provides the necessary functional properties.
Solution Approach 2:
The invention uses a composite coating system consisting of cyclic imide copolymer particles dispersed in a binder matrix. This composite structure combines the heat sealability and water barrier properties of the cyclic imide copolymer with the adhesion and flexibility provided by the binder, achieving both functional performance and recyclability.
2Reliability
If laminated thermoplastic layers are used to ensure no pinholes appear, then good barrier properties are achieved, but the minimum thickness requirement increases the weight of the packaging material
Solution Approach 1:
The invention employs a thin film coating containing cyclic imide copolymer particles that provides effective water barrier properties without requiring the minimum thickness of laminated thermoplastic layers. The particle-based coating system achieves barrier functionality at much lower thickness, reducing packaging weight while preventing pinhole formation.
3Reliability
If thermoplastic materials are used to provide heat sealability, then good sealing performance is achieved, but the materials are difficult to separate from paper or cardboard after use
Solution Approach 1:
The invention changes the chemical composition parameters of the heat sealable coating by using cyclic imide copolymer particles with specific functional groups that provide heat sealability through mechanisms different from conventional thermoplastics. This parameter change enables the coating to be applied in thinner layers that do not strongly bond to the paper or cardboard substrate, facilitating separation during recycling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cyclic imide coating enables efficient heat sealing and water barrier properties without the need for thick thermoplastic layers, facilitating recycling and reducing packaging weight while maintaining adhesion and sealing performance.
Implementation Method 1
The substrates can then be sealed to each other or to other substrates just by heating the heat sealable layer and by putting some pressure on the substrates
Implementation Method 2
The cyclic imide structures are quite unique as they have a high rigidity and polarity, though they have a good hydrophobicity
Implementation Method 3
the coating composition containing a cyclic imide is dispersed in the water phase and the coating composition containing a cyclic imide is a copolymer of cyclic imides and vinylic co-monomers
Data Source
AI summary
A process for applying a heat sealable layer to a substrate in which the substrate is provided with a coating composition containing a cyclic imide, which can be a maleimide, an itaconimide, a citraconimide or a 2,3 dialkyl maleimide. Preferably the coating composition is brought on the substrate from a water borne formulation in which the coating composition containing a cyclic imide is dispersed in the water phase and the coating composition containing a cyclic imide is a copolymer of cyclic imides and vinylic co-monomers, preferably a co-polymer of cyclic imides and styrene. The dispersed product in the water phase has a particle size between 20 and 500 nm, preferably between 30 and 200nm, and the particles have a core-shell structure.